Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Effects of Growth Conditions on Structural Properties of ZnO Nanostructures on Sapphire Substrate by Metal–Organic Chemical Vapor Deposition | Nanoscale Res Lett 2009 4 377-384 DOI S11671-009-9257-2 NANO EXPRESS Effects of Growth Conditions on Structural Properties of ZnO Nanostructures on Sapphire Substrate by Metal-Organic Chemical Vapor Deposition C. C. Wu D. S. Wuu P. R. Lin T. N. Chen R. H. Horng Received 4 December 2008 Accepted 8 January 2009 Published online 23 January 2009 to the authors 2009 Abstract ZnO was grown on sapphire substrate by metal-organic chemical vapor deposition using the diethylzinc DEZn and oxygen O2 as source chemicals at 500 C. Influences of the chamber pressure and O2 DEZn ratio on the ZnO structural properties were discussed. It was found that the chamber pressure has significant effects on the morphology of ZnO and could result in various structures of ZnO including pyramid-like worm-like and columnar grain. When the chamber pressure was kept at 10 Torr the lowest full width at half-maximum of ZnO 002 of 175 arc second can be obtained. On the other hand by lowering the DEZn flow rate the crystal quality of ZnO can be improved. Under high DEZn flow rate the ZnO nanowall-network structures were found to grow vertically on the sapphire substrate without using any metal catalysts. It suggests that higher DEZn flow rate promotes threedimensional growth mode resulting in increased surface roughness. Therefore some tip on the ZnO surface could act as nucleation site. In this work the growth process of our ZnO nanowall networks is said to follow the self-catalyzed growth mechanism under high-DEZn flow rate. Keywords ZnO Chamber pressure O2 DEZn ratio Nanowall networks Self-catalyzed C. C. Wu D. S. Wuu H P. R. Lin T. N. Chen Department of Materials Science and Engineering National Chung Hsing University Taichung 402 Taiwan ROC e-mail dsw@ R. H. Horng Institute of Precision Engineering National Chung Hsing University Taichung 402 Taiwan ROC Introduction ZnO is an attractive direct wide band gap Eg eV at 300 K semiconductor material for applications in
